The present invention relates generally to fasteners for plate material, and more particularly to a fastener system especially suited for composite plate or shell materials.
Existing commercially available fasteners are configured to withstand higher point loading than composite materials ordinarily can withstand, and generally require accessibility to both sides of the housing structure to which it is attached.
The invention disclosed herein comprises a fastener system for plate material and which is especially suited for mounting accessories to a housing constructed of composite laminate material. The fastener system of the invention is configured to be substantially flush with the surface of the housing in which it is disposed, yet provides convenient and structurally reliable means for attachment of an accessory to the housing. When not in use, the invention presents a smooth, streamlined surface on the housing, and therefore finds substantial utility for mounting of accessories to an engine housing, airfoil, fuselage or other surface to which flush mounting means is particularly desirable.
The invention includes an internally threaded flanged bushing insertable into a hole in the housing to which the fastener is applied and riveted thereto, and an internally and externally threaded insert within the bushing and presenting the internal threads thereof for attachment of a member to the housing. Tangs on the outwardly disposed end of the insert are bendable radially outwardly into spaces between crenelations in the outward end of the bushing to prevent the insert from inadvertently backing out of the bushing as a result of vibration or other applied force. The insert is replaceable without accessing the inner side of the housing structure. In a separate embodiment of the invention, a ball having a pair of protrusions and a diametric threaded hole is held within a flanged bushing by a slotted threaded insert such that the ball can rotate within prescribed limits about an axis containing the protrusions to accommodate off-axis or skewed mounting of a member to the housing, but is restrained against rotation about the axis of the insert. Both the ball and insert are easily removable from the bushing for replacement.
It is a principal object of the invention to provide an improved flush mounting fastener system.
It is another object of the invention to provide a flush mounting fastener system for plate material.
It is a further object of the invention to provide a flush mounting fastener system for accommodating a threaded attaching member having an off-center, skewed or variable axis.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.